Ianen, Vile Corruptor

Possession- When Ianen, vile corruptor enters the
battlefield, choose target creature an opponent
controls. Gain control of that creature, then exile
Ianen. For as long as you control that creature, it
gets +2/+2 and has flying, lifelink, and
deathtouch, and is a shade in addition to its
other types.
Whenever you gain life for the first time during
your turn, if Ianen is face-up in exile, you may
put it onto the battlefield.